feat(local-tool): Windows build fast path + 產物驗證

Makefile:
- 新增 exe-only target：只跑 iscc 打包 installer，不重 build wails/payload
- 拆出 _run-iscc 共用 recipe，exe 和 exe-only 都依賴它

bootstrap-windows.ps1:
- 偵測 visiona-local.exe / server.exe / ffmpeg.exe / python.tar.gz 都在時走 fast path
  只跑 make exe-only，省掉重複 wails build 的數分鐘
- 跑完驗證 dist\visiona-local-*-windows-x64.exe 確實存在，否則明確 Fail 並提示手動 iscc 指令

使用情境：使用者刪掉 dist\ 想重打 installer，再跑一次 bootstrap 就能秒出 .exe

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

local-tool/Makefile

@@ -27,7 +27,7 @@ PAYLOAD     := visiona-local/payload
         payload payload-macos payload-windows payload-linux \
         stage-macos stage-windows \
         wails-macos wails-windows wails-linux \
-        dmg exe appimage \
+        dmg exe exe-only _run-iscc appimage \
         dev dev-mock test lint fmt clean
 
 # ── 幫助 ───────────────────────────────────────────────────────────
@@ -458,7 +458,18 @@ dmg: wails-macos ## hdiutil UDZO → dist/visiona-local.dmg
 	@du -sh $(DIST)/visiona-local.dmg
 	@file $(DIST)/visiona-local.dmg
 
-exe: wails-windows ## ⚠️ 必須在 Windows 上跑：Inno Setup → dist/visiona-local-*-windows-x64.exe
+exe-only: ## 只跑 iscc 打包 installer（前置產物必須已存在），不重 build wails/payload
+	@if [ ! -f visiona-local/build/bin/visiona-local.exe ]; then \
+		echo "❌ visiona-local/build/bin/visiona-local.exe 不存在，請先跑 make wails-windows"; exit 1; \
+	fi
+	@if [ ! -f payload/windows/bin/visiona-local-server.exe ]; then \
+		echo "❌ payload/windows/bin/visiona-local-server.exe 不存在，請先跑 make payload-windows"; exit 1; \
+	fi
+	@$(MAKE) --no-print-directory _run-iscc
+
+exe: wails-windows _run-iscc ## ⚠️ 必須在 Windows 上跑：Inno Setup → dist/visiona-local-*-windows-x64.exe
+
+_run-iscc:
 	@ISCC_BIN="$$ISCC"; \
 	if [ -z "$$ISCC_BIN" ]; then \
 		if command -v iscc > /dev/null 2>&1; then ISCC_BIN=iscc; \

local-tool/scripts/bootstrap-windows.ps1

@@ -185,20 +185,39 @@ if ($msysIsccDir) {
 if ($msysIsccExe) {
     $bashParts += "export ISCC=`"$msysIsccExe`""
 }
+# 偵測前置產物是否已齊全 —— 齊全就走 fast path（只重跑 iscc），省 wails rebuild 幾分鐘
+$fastPath = (Test-Path 'visiona-local\build\bin\visiona-local.exe') -and `
+            (Test-Path 'payload\windows\bin\visiona-local-server.exe') -and `
+            (Test-Path 'payload\windows\bin\ffmpeg.exe') -and `
+            (Test-Path 'payload\windows\python\python.tar.gz')
+
+if ($fastPath -and ($Target -eq 'exe' -or -not $env:VISIONA_TARGET)) {
+    Log 'FAST PATH：前置產物齊全，跳過 vendor/payload/wails，只重跑 iscc 打包'
+    $bashParts += 'make exe-only'
+} else {
     $bashParts += 'make vendor-python-windows vendor-wheels-windows vendor-ffmpeg-windows vendor-ytdlp-windows'
     $bashParts += 'make payload-windows'
-
     switch ($Target) {
         'payload-windows' { }
         'wails-windows'   { $bashParts += 'make wails-windows' }
         default           { $bashParts += 'make wails-windows'; $bashParts += 'make exe' }
     }
+}
 
 $bashCmd = $bashParts -join ' && '
 
 & 'C:\msys64\usr\bin\bash.exe' -lc $bashCmd
 if ($LASTEXITCODE -ne 0) { Fail "build 失敗，exit code=$LASTEXITCODE" }
 
+# 驗證 dist 真的有 .exe 產出（exe target 是 phony，make 成功 != 產物存在）
+if ($Target -eq 'exe' -or $Target -eq 'default' -or -not $Target) {
+    $exeFiles = Get-ChildItem dist -Filter 'visiona-local-*-windows-x64.exe' -ErrorAction SilentlyContinue
+    if (-not $exeFiles) {
+        Fail "make exe 沒報錯，但 dist\ 下沒有 visiona-local-*-windows-x64.exe。往上捲看 iscc 輸出找原因，或直接跑：
+  & `"$env:LOCALAPPDATA\Programs\Inno Setup 6\ISCC.exe`" installer\windows\visiona-local.iss"
+    }
+}
+
 Log '完成 ✅'
 Log "產出位置：$(Join-Path (Get-Location) 'dist')"
 Get-ChildItem dist -ErrorAction SilentlyContinue | Format-Table Name, Length